Molded fibrous glass article



F. w. WALKER 2,938,737

May 31, 1960 MOLDED FIBROUS GLASS ARTICLE Filed Dec. 3, 1953 I N V ENTOR. Femm/cx W41. me

United States Patent i() MOLDED FIBRGUS GLASS ARTICLE Frederick W.Walker, Johnstown, Ohio, assignor to Owens-Coming Fiberglas Corporation,a corporation of Delaware Filed Dec. 3, 1953, Ser. No. 396,030

9 Claims. (Cl. 28B-150) This invention relates to the molding of fibrousglass masses with particular reference to the improvement of impactresistance characteristics and surface properties of automobile crashpads molded of such material.

In the molding of fibrous-glass articles such as automobile crash pads,it has been found dicult to provide smooth surfaces for the article ifthe density of the mass of bers in the final product is not abovecertain values. For instance, the density required to impart the desireddegree of smoothness to the mass of bers is often larger than that whichwill provide the degree of softness and resilience desired for impactpurposes.

Additionally, molded products of irregular contour require accumulationsof glass fibers to various thicknesses to impart to the final productthe desired rigidity and strength associated with the heavier densitymaterials. In effecting such a pile-up of fibrous glass in molds ofirregular contour, it will be recognized that diiculty exists inassuring a uniform density of matter throughout the product andaccordingly the surface hardness varies throughout the product dependingupon the varying densities thereof. These problems arise particularlybecause of the lack of ovvability of brous glass masses in the mold inthe manner of uid materials such as molten plastics.

VIn'viev'v of the foregoing, it is an object of the present invention toprovide a method and means for manufacturing molded fibrous-glassarticles having surfaces controllably smooth and softv even when thefibrous glass mass is of dense character.

'It' is another more specific object of this invention to provide amethod and means whereby an automobile crash pad can be constructed ofmolded glass-fiber masses formed into a' rigid structure having animpact distributing surface layer of soft resiliently associated fibersin integral relationship therewith.

-Another object' of this invention is to provide a method and means forimparting improved depression recovery properties to an automobile crashpad of molded fibrous glass.

The thickness of glass fiber accumulations piled within a cavity formolding operations is determined by the density necessary in the finalarticle to effect the strength characteristics desired and dictated byuse, as well as the number and thickness of bers necessary to providethe rigidity and surface texture desired. The densities of the finalmolded product usually vary throughout the article especially when thearticle is intricate in shape, since it is extremely dicult to insertthe precise number or pile-up of bers in each incremental area of themold to effect uniformity of density throughout. Additionally, differentdensities are Often desired in different parts of an intricately shapedarticle, the greater densities'being desired in those portions ofthearticle where greatest strength is necessary. Usually with Vvariationsin density existing throughout, surface texture'and hardness variationsalso exist throughout the article. Such Tice variations are mostfrequently undesirable and in some instances, the surfacecharacteristics of the whole or portions of the article are definitelyopposed to those necessary with respect to the functional aspects of thearticle.

In accordance with the principles of this invention, the entire surfaceor localized areas may be treated to impart uniformity in texture orhardness, or may be treated so as to obtain a degree of softness andresilience dcsired while still providing the density in the differentportions of the article consistent with the strength and smoothness orwrinkle freeness required. In general, to obtain these results, articlesmolded according to the principles of the present invention are moldedto the density required to prevent presence of surface wrinkles or foldsin the final article and then are subjected to a working to impart thedegree of softness desired in the.

exposed surfaces. It frequently occurs that the density required toprevent wrinkling of the surface is greater than that necessary toprovide the strength required in the article. Regardless, according tothe present invention, the degree of softness and resilience of a lowerdensity material can be imparted by properly working the surface.

Working can be accomplished by passing a roller over the surface of themolded article to break the bonds between surface fibers joined togetherat their interstices during the mold curing operation. Bond breakage maybe effected to considerable depths below the surface by Vapplication ofthe degree of pressure necessary to provide the amount of bond breakageby a single passage of the roller thereover, or by repetitively passingthe roller back and forth over the surface with a pressure 0f lesserdegree until the desired feel is imparted to the surface.

Even when an article molded of fibrous glass is treated to impartdesired resilience to the surface, the depression recovery and surfaceappearance may not be that desired for particular applications to whichthe object is to be adapted. To improve the depression recoveryproperties, it has been found that a membrane of rubberlike materialsuch as a neoprene latex sprayed over the surface and integrallyassociated therewith will in many instances render the article moreadaptable for use. Such a surface membrane, beside improving recoverycharacteristics, is of advantage in providing improved appearance whilesimultaneously acting as a retainer sur- -face for any loose fiberstending to separate from the surface.

The automobile crash pad of the present invention is a general typeadapted to lay over the top of the instrument panel of the vehicle andto provide a soft resilient leading edge to distribute impact forces andto cushion the jar in instances such as when a child is bodily moved andits head is thrown forward into the panel on sudden application ofbrakes.

Figure l shows a platen-matedvmold with bers accumulated in the cavity;

Figure 2 shows the molded fibrous glass crash pad with a roller beingpassed over the leading edge to eect breakage of bonds at interstices ofbers in the surface layer to produce the soft resilient property desiredat the leading edge;

Figure 3 shows in cross section the mold of Figure l in open conditionwith fibers in mat and strip form laid therein to different depths priorto closure;

Figure 4 shows in cross section the mold of Figure l in closed conditionfor curing of crash pad; and

Figure 5 shows the molded crash pad in part illustratingv gescheit'fibers or effect the breakage of bonds to levels in the depth of the padbeyond those which are desirable.

It has been found, however, that a molded fibrous article has tremendousabsorption properties so as to require an excessive and costly amount ofmembraneforming fluid. To remedy this condition when a neoprene latex isused, a powdery material such as talc or starch is added to the latexbefore spraying over the fibrous surface. This reduces the absorptioncharacteristics considerably, causing the fluid to remain primarily atthe surface where it best provides the depressionrecoverycharacteristics for the molded article. A material which has beensuccessfully used in this manner comprises one pound of processed starchadded to a gallon of neoprene latex mix, the mix being a Waterdispersion of 42 percent solids. Such a surface coating material can besprayed on and cured at 450 F. in a separate relatively short cycle ofthe order of three minutes. To further enhance the appearance of theproduct,l a material such as rayon ocking may be sprayed over thesurface of the mold-cured pad on a lm of air drying adhesive or oneIthat cures at moderate temperatures to give the surface a soft texturebeyond that provided by the soft fibrous glass.

A soft resilient membrane coating can also be imparted to the articledirectly in the molding process by resorting to a material such as aplasticized vinyl polymer. In providing such a surface, the moldsurfaces may be first sprayed with a coating of material such assilicone which will act as a parting agent to enable easy removal of thefinished article after molding. The plastisol is then sprayed over thesilicone coating and the fibers inserted thereover for the moldingoperation. It should be noted that this method of providing a surfacemembrane has Ithe advantage of protecting the polished metal surface ofthe mold during loading of the mold. In this respect, the plastisolprovides a semi-hard surface for receipt of the fibers when sprayed overthe mold surfaces While they are hot. Additionally, the surface texturemay be modified in the molding operation by providing embossments in themold to produce surface effects such as simulated leather.

While the present invention has been described in connection with aparticular molded fibrous glass product, it will be obvious to thoseskilled in the art that the principles have broad application to othermolded fibrousglass articles and that changes and modifications may bemade Without departing from this invention in its broader aspects. Forinstance, the invention may be used in the manufacture of articles suchas dunnage forms, structural parts of items such as refrigeratorcabinets, and the like. It is therefore the aim in the appended claimsto cover all such changes and modifications as fall within the truespirit and scope of this invention.

I claim:

l. The method of producing a molded fibrous glass article comprisingassembling glass fibers with heatcurable resin material in a mold, saidassembly of fibers being accumulated to thicknesses in the mold such aswill assure wrinkle free smoothness in the molded article, compressingsaid assembly into the desired shape, heating the compressed mass whileretained in the desired shape to cure the resin and cause bonding of thepoints of fiber contact, and working the surface masses of the newlybonded bers of the article by exerting compressive forces over at leastpart of the surfaces of the molded article such as will break at least aportion of the bonds for a relatively short depth at the surface of thearticle to provide portions having a fiber surface layer softer thanthat originally provided upon curing of the resin.

2. The method of producing a molded fibrous glass article comprisingforming an assembly of glass fibers having a heat-curable bondingmaterial incorporated therewith in a mold, said assembly of fibers beingaccumulated to different thicknesses in the mold in accordance withdensities desired in various `-portions of the molded article,compressing said assembly into the desired shape, heating the compressedmass While retained in the desired shape to cure the bonding materialand cause bonding between the glass fibers at their points of contact,and providing an integral surface layer of softer, more resilientcharacter for the article by exerting compressive forces on the surfaceof magnitude which will break at least a portion of saidbonds in onlythe surface layer of fibers, and applying a surface membrane ofresilient material in integral relation with the surface layer of saidarticle whereby the depression recovery property of said article isimproved.

3. In a method of producing a molded article of fibrous glass, the stepscomprising forming an assembly of glass fibers having a heat-curablebonding material incorporated therewith, compressing said assembly intopredetermined shape, heating the compressed mass while retained in thedesired shape to cure the bonding material and cause bonding between theglass fibers at their points of contact, and providing an integralsurface layer of fibers of softer, more resilient character than theunder mass of bonded fibers of the article by exerting localizedcompressive forces on the vsurface of such magnitude as to break atleast a portion of said bonds in only the top layer of fibers.

4. In the method of producing a molded fibrous glass article, the stepsof providing a smooth surface for the article comprising assemblingfibers coated with uncured resin in the forming cavity of a mold insufiicientnumbers in proportion to the various thicknesses of the cavityto provide a sufficiently close association of fibers during curing ofthe resinto impart the smoothness desired in the molded article, andworking the smooth surface by exerting localized compressive forcesthereon to unbond a layer of fibers immediately thereunder to impart adegree of surface softness correspondingto a lower density accumulationof fibers.

5. In the process of producing a relatively dense rigid molded articleof interbonded glass bers, the method of imparting an improveddepression recovery and shock absorbing surface comprising the steps ofapplying a stretchable resilient membrane over said surface and workingthe membrane against the fibers immediately thereunder by exertinglocalized compressive forces on the membrane to break at least a portionof the bonds between fibers of the surface to impart a desired degree ofsofter resilience to the surface than is characteristic of the generaldensity of the article.

6. An automobile crash pad made of molded brous glass, comprising anelongated generally flat member having contours to match the top surfaceof an instrument panel of an automobile, said pad having an overhangingleading edge to cover the top front edge of the instrument panel, saidleading edge being of density to prevent bottoming on normal impact andbeing provided a relatively soft resilient surface layer of fibers toeffect distribution of forces of impact.

7. An automobile crash pad moldedV of fibrous glass, comprising aplurality of interbonded glass fibers molded to form a pad having ageneral shape arranged to match the top of an automobile instrumentpanel, said pad having an overhanging leading edge to cover the topfront edge of the instrument panel, said leading edge having a densitysuicient to prevent bottoming on normal impact and having a softer toplayer of fibers to effect distribution of forces of impact, and astretchable membrane integrally associated with the top fibers of atleast the leading edge of said pad.

8. An article molded of fibrous glass comprising a mass of glass bersclosely interbonded to a density sufficient t0 impart rigidity thereto,said article having a surface layer including unbonded bers suicient innumber to impart a greater resiliency and softer feel to such surfacethan is characteristic of the general density of the interior of thearticle, and a stretchablemembrane inte- 'grally associated with themore .resilient slrface layer of fibers to improve thedepressionrecovery characteristics vof saidsurface. t f* Y Y 9. Themethod of prodcing a molded librous glass article comprising forming anassembly of 'glass ibers having a heat-curable bonding materialincorporated therewith in a mold cavity, said stepY of forming anassembly of-glass bers comprising laying up in said cavity compressiblebrous layers of different lengths, Widths and thicknesses in alignedrelation in accordance With cavity dimensions and densities Vdesired inthe molded article, each such layer consisting of a mass of randomlyforiented discontinuous 'glass ibe'rs compressing said-assembly todesired shape-in said cavity, Aheating/thetcorripressed VmassV Whileretained in said shape to "cre the bonding material and cause 'bondingof the Vglass bers Yat their points of contact, and spraying adispersion of airelastomei'ic material into' adhering relation withV asurface of the article to form a stretchable resilient surface ,membraneinin'timate relation over such surface whereby FOREIGN PATENTSGretritain eb.l'3, i' Canada Dec. 12,

1. THE METHOD OF PRODUCING A MOLDED FIBROUS GLASS ARTICLE COMPRISINGASSEMBLING GLASS FIBERS WITH HEATCURABLE RESIN MATERIAL IN A MOLD, SAIDASSEMBLY OF FIBERS BEING ACCUMULATED TO THICKNESSES IN THE MOLD SUCH ASWILL ASSURE WRINKLE FREE SMOOTHNESS IN THE MOLDED ARTICLE, COMPRESSINGSAID ASSEMBLY INTO THE DESIRED SHAPE, HEATING THE COMPRESSED MASS WHILERETAINED IN THE DESIRED SHAPE TO CURE THE RESIN AND CAUSE BONDING OF THEPOINTS OF FIBER CONTACT, AND WORKING THE SURFACE MASSES OF THE